Injection molding machine and viscosity measurement method

Abstract

An injection molding machine and a viscosity measurement method of the disclosure are provided with an injection cylinder to which a viscosity measurement unit is attachable and detachable and a control device. When setting an inner diameter of the injection cylinder or an outer diameter of the injection shaft as D. For a capillary installed to the viscosity measurement unit, a capillary inner diameter is set as d. By respectively using three or more values γ k of the shear rate, k being a natural number, the control device is configured to calculate injection velocities V k based on Formula (1) and automatically sets a value of the injection velocity V k within a predetermined range, among the calculated injection velocities, as an injection velocity at a time of viscosity measurement. [ Formula ⁢ ( 1 ) ] V k = d 3 8 ⁢ D 2 ⁢ γ k ( 1 )

What is claimed is: 
     
         1 . An injection molding machine, comprising:
 an injection cylinder, to which a viscosity measurement unit is attachable and detachable;   an injection shaft, inside the injection cylinder;   an injection driving device, driving the injection shaft; and   a control device, controlling the injection driving device, so as to drive the injection shaft forward and rearward,   wherein, when setting an inner diameter of the injection cylinder or an outer diameter of the injection shaft as D, and, for a capillary die and/or a slit die installed to the viscosity measurement unit, a capillary inner diameter is set as d and a slit length and a slit width are respectively set as B and H, the control device is configured to, by respectively using three or more values γ k  of shear rate, k being a natural number, calculate injection velocities V k  based on Formula (1) or (2) below and automatically set a value of the injection velocity V k  within a predetermined range, among the calculated injection velocities, as an injection velocity at a time of viscosity measurement   
       
         
           
             
               [ 
               
                 Formula 
                 ⁢ 
                     
                 
                   ( 
                   1 
                   ) 
                 
               
               ] 
             
           
         
         
           
             
               
                 
                   
                     
                       V 
                       k 
                     
                     = 
                     
                       
                         
                           d 
                           3 
                         
                         
                           8 
                           ⁢ 
                           
                             D 
                             2 
                           
                         
                       
                       ⁢ 
                       
                         γ 
                         k 
                       
                     
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
         
           
             
               [ 
               
                 Formula 
                 ⁢ 
                     
                 
                   ( 
                   2 
                   ) 
                 
               
               ] 
             
           
         
         
           
             
               
                 
                   
                     
                       V 
                       k 
                     
                     = 
                     
                       
                         
                           2 
                           ⁢ 
                           
                             BH 
                             2 
                           
                         
                         
                           3 
                           ⁢ 
                           π 
                           ⁢ 
                           
                             D 
                             2 
                           
                         
                       
                       ⁢ 
                       
                         
                           γ 
                           k 
                         
                         . 
                       
                     
                   
                 
                 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
       
     
     
         2 . The injection molding machine as claimed in  claim 1 , wherein the viscosity measurement unit comprises:
 the capillary die and/or the slit die;   a measurement cylinder, to which the capillary die and/or the slit die is installed; and   a pressure sensor, measuring a pressure of a molding material flowing in the measurement cylinder.   
     
     
         3 . The injection molding machine as claimed in  claim 2 , wherein the viscosity measurement unit is configured so that two or more dies of different specifications are able to be installed to the viscosity measurement unit. 
     
     
         4 . The injection molding machine as claimed in  claim 2 , wherein, the control device is configured to, for each value of the injection velocity V k  within the predetermined range, calculate a viscosity η k  of the molding material in accordance with the value of the injection velocity V k  by using a measurement value obtained from the pressure sensor by operating the injection driving device. 
     
     
         5 . The injection molding machine as claimed in  claim 4 , further comprising a display device, wherein the control device is configured to display the value of the injection velocity V k  within the predetermined range and a value of the viscosity η k  on the display device. 
     
     
         6 . The injection molding machine as claimed in  claim 5 , wherein the viscosity measurement unit comprises a temperature sensor measuring a temperature of the molding material flowing in the measurement cylinder,
 the control device, for each value of the injection velocity V k  in the predetermined range, obtains an actual measurement value T k  of the temperature of the molding material obtained from the temperature sensor by operating the injection driving device, and   the control device further displays the actual measurement value T k  of the temperature of the molding material on the display device.   
     
     
         7 . The injection molding machine as claimed in  claim 5 , wherein the control device is configured to draw and display, on the display device, a graph illustrating a relationship between a value γ k  of the shear rate and the value of the viscosity η k . 
     
     
         8 . The injection molding machine as claimed in  claim 7 , wherein the viscosity measurement unit comprises a temperature sensor measuring a temperature of the molding material flowing in the measurement cylinder,
 the control device, for each value of the injection velocity V k  in the predetermined range, obtains an actual measurement value T k  of the temperature of the molding material obtained from the temperature sensor by operating the injection driving device, and   the control device further displays the actual measurement value T k  of the temperature of the molding material on the display device.   
     
     
         9 . The injection molding machine as claimed in  claim 5 , wherein the control device is configured to draw and display, on the display device, a graph illustrating a relationship between a value obtained by correcting the value γ k  of the shear rate with Rabinovich correction and a value obtained by correcting the viscosity η k  with Rabinovich correction. 
     
     
         10 . The injection molding machine as claimed in  claim 5 , wherein the three of more values γ k  of of the shear rate are values selected within a range of 1*101 sec-1 or more and 5*105 sec-1 or less, where * represents multiplication, and
 the predetermined range of the injection velocity is 0.05 mm·sec −1  or more and 200 mm·sec −1  or less. 
 
     
     
         11 . The injection molding machine as claimed in  claim 10 , wherein the three or more values γ k  of of the shear rate are five values, which are R*10 1  sec −1 , R*10 2  sec −1 , R*10 3  sec −1 , R*10 4  sec −1 , and R*10 5  sec −1 , R being a number of 1 or more and 5 or less. 
     
     
         12 . A viscosity measurement method, provided for the injection molding machine as claimed in  claim 2 , the viscosity measurement method comprising:
 a process of causing the molding material to flow in the capillary die or the slit die installed to the measurement cylinder via the measurement cylinder of the viscosity measurement unit having the pressure sensor from the injection cylinder at the injection velocity V k ;   a process of acquiring a pressure value of the molding material flowing in the measurement cylinder by using the pressure sensor; and   a process of calculating a viscosity η k  in accordance with the injection velocity V k  by using the pressure value,   wherein the process of causing the molding material to flow comprises a process of, by using the control device of the injection molding machine, calculating the injection velocity V k  in accordance with each of the three or more values γ k  of the shear rate set in advance based on Formula (1) or (2), and automatically setting the value of the injection velocity V k  in the predetermined range, among the calculated injection velocities, as the injection velocity at the time of viscosity measurement.   
     
     
         13 . The viscosity measurement method as claimed in  claim 12 , wherein in the process of automatically setting the injection velocity V k , the three or more values γ k  of of the shear rate are values selected within a range of 1*10 1  sec −1  or more and 5*10 5  sec −1  or less, where * represents multiplication, and the predetermined range of the injection velocity is 0.05 mm·sec −1  or more and 200 mm·sec −1  or less. 
     
     
         14 . The viscosity measurement method as claimed in  claim 13 , wherein the three or more values γ k  of of the shear rate are five values, which are R*10 1  sec −1 , R*10 2  sec −1 , R*10 3  sec −1 , R*10 4  sec −1 , and R*10 5  sec −1 , R being a number of 1 or more and 5 or less. 
     
     
         15 . The viscosity measurement method as claimed in  claim 12 , wherein the process of obtaining the pressure value comprises a process of switching among two or more dies, each of which is a destination for introducing the molding material via the measurement cylinder, and obtaining the pressure values individually. 
     
     
         16 . The injection molding machine as claimed in  claim 1 , further comprising a display device, wherein the control device is configured to display the value of the injection velocity V k  within the predetermined range on the display device. 
     
     
         17 . The injection molding machine as claimed in  claim 1 , wherein the three of more values γ k  of of the shear rate are values selected within a range of 1*10 1  sec −1  or more and 5*10 5  sec −1  or less, where * represents multiplication, and
 the predetermined range of the injection velocity is 0.05 mm·sec −1  or more and 200 mm·sec −1  or less. 
 
     
     
         18 . The injection molding machine as claimed in  claim 17 , wherein the three or more values γ k  of of the shear rate are five values, which are R*10 1  sec −1 , R*10 2  sec −1 , R*10 3  sec −1 , R*10 4  sec −1 , and R*10 5  sec −1 , R being a number of 1 or more and 5 or less. 
     
     
         19 . The injection molding machine as claimed in  claim 1 , wherein the injection molding machine is a screw preplasticating injection molding machine, and
 the injection shaft is a plunger.   
     
     
         20 . The injection molding machine as claimed in  claim 1 , wherein the injection molding machine is an inline screw type injection molding machine, and
 the injection shaft is an inline screw.